More Cardboard Boxes

By Henry, on January 5th, 2014

After having built small cardboard cases for single computers, I tried building single cases for multiple machines. The idea is to share the power supply to reduce cost and increase packing density. For cost reasons, I’ve stuck with microATX motherboards so far, but Mini-ITX seems interesting as they’re smaller and only a little more expensive.

A year ago, I built four Intel LGA1155 systems in a box. Now I’ve added four AMD AM2+/AM3+ systems in a box. Continuing with the unoriginal naming scheme, these systems are named box3 through box6 and box7 through box10, respectively.

Box3-6: Four Intel systems in a box

Box7-10: Four AMD systems in a box

Size comparison: Intel system (bottom) is more compact.

The Intel systems are more compact because they use smaller heatsinks. The AMD CPUs not only consume more power, but they also need to be kept cooler (around 70°C AMD vs. 100-105°C Intel), causing AMD stock heatsinks to be bigger and louder (7000 RPM vs. ~2100 RPM fans) to handle the greater cooling requirements. The high power consumption meant that there was basically no power headroom to overclock the AMD systems, and I even disabled TurboCore to prevent Vcore from increasing…

box3

box4-6

box7

box8

box9

box10

Processor

Core i5-2500K @ 4.2 GHz

Core i5-3570K @ 4.2 GHz

Phenom X4 9550 @ 2.2 GHz

Phenom II X6 1090T @ 3.4 GHz

FX-8120 @ 3.4 GHz

FX-8320 @ 3.4 GHz

Motherboard

Biostar TZ77MXE

Asus M3A78-EM

Gigabyte 78LMT-USB3

Power Supply

Antec EA-650 Platinum

Antec EA-650 Platinum

Cooling

4×Stock HSF, 2×Arctic F12 PWM

4×Stock HSF, 2×Arctic F12 CO

Volume

18.8 L

26.7 L

Weight

I didn’t measure

17 lbs

Max Power (wall)

515 W

640 W

Completed

November 2012

January 2014

Power Supply Sharing

ATX power supplies are turned on using Pin 16, PS_ON#. The ATX specification seems to describe this signal as an open-drain output by the motherboard, where the power supply uses a pull-up resistor to hold the line high (+5V). This means it’s possible to just wire all of the ATX connectors together, and the power supply will stay on as long as any of the motherboards pull PS_ON# low. I haven’t noticed any adverse effects of applying power to a motherboard that isn’t requesting it.

More Photos

Box7-10: Almost complete! SATA drives are placed next to the power supply.

Rear of box7-10

Box3-6 during construction, with the top motherboard tray visible.

Motherboards slide in from the front of the case on rails made from bamboo skewers.

Box7-10: I was short on skewers, so there was some cost-cutting. There are half as many horizontal skewers compared to box3-6.

Close-up of a motherboard sitting in a rail made from three skewers glued together.